1. Field of the Invention
The present invention relates to an electronic power steering apparatus that generates a steering assist force by an electric motor.
2. Description of Related Arts
In a rack assist type electronic power steering apparatus, the rotation of an electric motor is decelerated through a pulley/belt mechanism, and is then converted into the axial movement of a rack shaft through a screw ball mechanism enclosing a rack shaft (see JP-B-4-28583, for example).
In this case, a belt is interposed in a power transmission path between the electric motor and the rack shaft. Accordingly, a shock load and vibration from the rack shaft are not transmitted to the electric motor.
However, vibration may be generated in the belt due to fluctuations in the tension of the belt, and transmitted to a housing to propagate into a vehicle chamber, to be noise.